Surface air temperatures for July 2017

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Surface air temperatures for July 2017

Surface air temperature anomaly for July 2017 relative to the July average for the period 1981-2010. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service) Download the original image

July 2017 was very much warmer than the 1981-2010 average over southern Europe, where wildfires have troubled many countries and sustaining water supplies has become a challenge in places, such as reported for Rome. Conversely, temperatures were well below average over most of the north of the continent. An exception was the far north-west of Russia, where temperatures were substantially above average, as they were in 2016. Aside from this region, the general contrast between south and north in essence continues a pattern that was present over Europe in April, May and June.

Summer heat-wave conditions prevailed over the western USA and south-western Canada, over Israel Jordan and northern Saudi Arabia, and over Mongolia and northern and eastern China. The city of Shanghai was reported to have had its warmest day on record.

Australia as a whole experienced its warmest July maximum temperatures on record. Much of South America and Africa were also warmer than average in July 2017, but eastern Brazil was colder than normal. The below-average temperatures over northern Europe were part of a band that extended around much of the northern hemisphere, including Greenland and the northern North Atlantic Ocean. Temperatures were also below average over much of the Antarctic and some oceanic regions of the southern hemisphere, although pronounced warm anomalies occurred where sea-ice cover was lower than usual around Antarctica.

Surface air temperature anomaly for August 2016 to July 2017 relative to the average for 1981-2010. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service) Download the original image

Average temperatures for the twelve-month period from August 2016 to July 2017 were:

most above the 1981-2010 average in the Arctic;

much above average offshore of West Antarctica, over much of North America, and over south-western Europe, the Middle East, north-western and central Africa, and eastern and southern Asia;

higher than average over most other areas of land and ocean;

lower than average over only a few oceanic and land areas.

Monthly global-mean and European-mean surface air temperature anomalies relative to 1981-2010, from January 1979 to July 2017. The darker coloured bars denote the July values. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service)Access to data Download the original image

July 2017 extended the spell of exceptional global warmth that has now lasted since mid-2015. It was:

0.45OC warmer than the average July from 1981-2010;

the second warmest July on record, by a margin of about 0.1 OC;

a little under 0.1OC cooler than July 2016.

The warmest instances of each month of the year occurred from October 2015 to September 2016. Each of the ten months from October 2016 to July 2017 has been the second warmest on record for that month of the year.

The largest anomalies in European-average temperatures occur in wintertime, when values can vary substantially from month to month. The average for Europe in July 2017 was close to the 1981-2010 norm.

Running twelve-month averages of global-mean and European-mean surface air temperature anomalies relative to 1981-2010, based on monthly values from January 1979 to July 2017. The darker coloured bars are the averages for each of the calendar years from 1979 to 2016. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service)Access to data Download the original image

Averaging over twelve-month periods smooths out the shorter-term variations. Globally, the twelve-month average from August 2016 to July 2017 is 0. 56°C above the 1981-2010 average. The warmest twelve-month period on record is from October 2015 to September 2016, with a temperature 0.64°C above average. 2016 is by far the warmest calendar year on record: its global temperature of 0.62°C above the average for 1981-2010 compares with values of 0.44°C and 0.35 °C respectively for 2015 and 2005, the two next warmest calendar years.

The spread in the global averages from various temperature datasets has been unusually large in 2016 and 2017, due to differences in the extent to which datasets represent the relatively warm conditions that have predominated over both the Arctic and the Antarctic. Spread is also high for the year 2005. Nevertheless, there is general agreement between datasets regarding:

the exceptional warmth of 2016, and to a lesser extent 2015;

the overall rate of warming since the late 1970s;

the sustained period of above-average temperatures from 2001 onwards.

There is more variability in average European temperatures, but values are less uncertain because observational coverage of the continent is relatively dense. Twelve-month averages for Europe were at a high level from 2014 to 2016. They have fallen over the past twelve months, but remain well above the 1981-2010 average. The warmest twelve-month period occurred from July 2006 to June 2007.